Zirconia sintered body has high strength, whereby it has been used as dental materials. When the zirconia sintered body is used as a dental material, it is required to have not only high strength but also aesthetic properties similar to those of natural teeth.
Heretofore, to obtain a zirconia sintered body aesthetically comparable to natural teeth, a dental material prepared by laminating, on the surface of zirconia sintered body, other materials so as to adjust its color tone has been reported (Patent Document 1). However, since such a dental material is a composite material made of a glass material having a strength different from that of zirconia, its strength has not been sufficient for a dental material.
Therefore, a zirconia sintered body for dental materials which has increased aesthetic properties, without laminating other materials, while maintaining its strength has been studied.
For example, it has been reported that a zirconia sintered body having a translucency equivalent to that of natural teeth can be prepared by imparting translucency thereto. Patent Documents 2 and 3 disclose a zirconia sintered body, which will be used as a dental material as it is, having high strength and high translucency. However, although such a zirconia sintered body was found to show a translucency equivalent to that of natural teeth, its bright white color tone derived from zirconia was found to be different from the color tone of natural teeth.
Further, a colored zirconia sintered body for dental materials which contains oxides as a coloring agent has been reported (Patent Document 4). However, in such a colored zirconia sintered body, visible lights are absorbed by a coloring component contained therein. In addition, the translucency of such a sintered body is low since the coloring component inhibits the sintering process. Accordingly, such a colored zirconia sintered body was found to have a translucency and color tone different from those of natural teeth, and also have low strength.